Arrowhead with pivotally mounted blades

ABSTRACT

A blade-opening arrowhead wherein at least one blade, preferably two blades, are pivotally mounted with respect to a blade carrying body. A bias force is used to urge an engagement member against a corresponding blade. The bias force is preferably selected so that each blade remains in a normally closed position during flight or during handling of the arrowhead, but yet responsively and quickly moves to a fully open position upon impact or when a sufficient opening force is applied to the blade.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a blade-opening arrowhead having at least oneblade which is pivotally mounted to move between a fully open positionand a fully closed position wherein there is a positive snap lockingblade retention system that maintains each blade in a normally closedposition.

2. Description of Prior Art

In the archery industry, many manufacturers have attempted tosimultaneously achieve an arrowhead that has aerodynamic propertiessimilar to those associated with non-bladed arrowheads known as fieldpoints or nib points, while also achieving effective cutting areasprovided by bladed arrowheads, which are often referred to asbroadheads. Broadhead blades which are exposed during flight oftenresult in undesirable steering of the front portion of the arrow,causing the arrow to deviate from a perfect flight path that coincideswith a longitudinal axis of the arrow shaft, when loaded or drawn withinan archery bow.

By reducing the surface area of a broadhead blade, the undesirablesteering effects can be reduced. However, when the surface area of ablade is significantly reduced, the structural integrity is diminished.Also, by reducing the surface area of a blade, the cutting area within atarget or game is also reduced, resulting in a less effective entranceand exit wound.

Conventional blade-opening arrowheads have been designed so that asubstantial portion of the blade is hidden within the body of thearrowhead, such as during flight of the arrow. Upon impact, such bladesare designed to open and thereby expose a cutting surface or sharp edgeof the blade. When the blades of such conventional arrowheads are closedand substantially hidden within the body, the exposed surface area isreduced and thus produces relatively less undesirable steering effects.

Many of such conventional blade-opening arrowheads rely upon complexmechanisms, some of which fail to open because of a significant holdingor closing force that must be overcome, and others that open prematurelybecause of structural deficiencies within the blade carrying body thatfail upon impact, resulting in non-penetration of the arrow. With suchrelatively complex mechanisms, dirt or other materials that may entersuch conventional arrowheads can affect the reliability of thearrowhead, particularly after prolonged use.

Other conventional broadheads which have blades partially hidden withinthe body use annular retaining rings, such as O-rings, wraps, bands andthe like, in order to maintain the blades in a closed position duringflight. Upon impact, such annular retaining rings are designed to sheeror roll back along the opening blades, in order to allow the blades tomove to an open position. Quite often, such conventional annularretaining rings are prone to cracking, particularly when the elastomermaterial dries out. Upon release of a bowstring, the rapid accelerationand thus significant opening forces move the blades in an openingdirection. The conventional annular retaining rings counteract suchopening forces. However, when the ring material dries out, cracks or isotherwise damaged, the blades may open prematurely, resulting insignificant danger or injury to the archer.

Many of the annular retaining rings are designed for one use and thusmust be replaced after each use. In addition to the cost involved withsupplying such consumable item, the annular retaining rings aredifficult and time-consuming to install, such as when hunting,particularly during inclement weather. Furthermore, the materialproperties of such conventional annular retaining rings can be affectedby temperature changes, thereby resulting in different bias forces thatcause the blade to open prematurely or to not open when desired.

U.S. Pat. No. 5,090,709 teaches an arrowhead with extendable bladespositioned adjacent fixed blades. The extendable blades are pivotallyconnected to a body. A ring releasably holds the extendable bladeswithin corresponding slots within the body.

U.S. Pat. No. 5,286,035 teaches an arrowhead that has a sharpened blade,pivotally mounted within a slot in the body of the arrowhead. A rubberO-ring is used to hold the blade in a temporarily stationary position,centered within the slot in the body. Upon impact, the rubber O-ringslides rearward onto the arrow shaft and allows the blade to pivot toeither side of the arrowhead body.

U.S. Pat. Nos. 5,112,063, 4,998,738 and 5,082,292 disclose a broadheadwith deployable cutting blades that are connected by pivot pins to aplunger. The cutting blades pivot between an open cutting position and aclosed non-barbed position.

U.S. Pat. No. 5,102,147 discloses a ballistic broadhead assembly thathas blades pivotally mounted on an actuating plunger. Upon impact, theactuating plunger thrusts the blades outwardly and forwardly.

It is apparent from the conventional blade-opening arrowheads that thereis a need for a blade-opening arrowhead that maintains each blade in aclosed and locked position during flight, and that allows the blades toresponsively free-wheel to an open position when a sufficient openingforce is applied to the blade. It is also apparent that there is a needfor a blade-opening arrowhead that does not require consumable items,such as O-rings, wraps, bands and the like, to hold the blades in aclosed position.

SUMMARY OF THE INVENTION

It is one object of this invention to provide an arrowhead withpivotally mounted blades that can be maintained in a normally closedposition, wherein a major portion of each blade is housed within a slotof the blade carrying body, and that pivot rearwardly into a fully openposition upon target impact or upon experiencing a similar openingforce.

It is another object of this invention to provide a blade-openingarrowhead wherein various types of springs and engaging elements can beused to maintain pivotally mounted blades in a normally closed positionbut which also provides a bias force that can be overcome by an openingforce applied to the blade when in the closed position.

It is still another object of this invention to eliminate the need forconsumable mechanical components, such as O-rings, bands, wraps and thelike, which are conventionally used to maintain opening blades in aclosed position during flight and also during handling of the arrowhead.

It is yet another object of this invention to provide an improved designfor a blade which is used in a blade-opening arrowhead.

The above and other objects of this invention are accomplished with anarrowhead that has a blade carrying body, which is also known to thoseskilled in the art as a ferrule. At least one blade, preferably 2-4blades, are each pivotally mounted with respect to the blade carryingbody. In one preferred embodiment according to this invention, a pivotshaft is mounted with respect to the blade carrying body. For example,the pivot shaft can be completely positioned within the blade carryingbody so that no portion of the pivot shaft extends beyond the skin oroutside surface of the blade carrying body. In such preferredembodiment, each blade has a slot or a through hole in which the pivotshaft is matingly engaged, thus allowing the blade to pivot with respectto the blade carrying body.

Each blade preferably pivots between a normally closed position and afully open position. In the normally closed position, each blade ispreferably positioned such that a major or significant portion of theblade is housed within a slot formed by the blade carrying body. In thefully closed position, a sharp edge of the blade is preferablynon-exposed for safety reasons. A major or significant portion of eachblade is preferably housed within the blade carrying body, so thatduring flight the arrowhead according to this invention achieves veryfavorable aerodynamic qualities and characteristics.

In the fully open position, each blade preferably has a blunt edge,opposite the sharp edge, which abuts or contacts a correspondinglymateable base edge formed by the blade carrying body, preferably in anarea where the blade carrying body forms the slot that houses the blade.In one preferred embodiment according to this invention, the blunt edgeof the blade has an overall generally convex arcuate section and theblade carrying body has a corresponding generally concave arcuatesection. Thus, when the blade is in a fully open position, there ispreferably intimate contact between the blunt edge of the blade and thebase edge of the blade carrying body. By providing increased surfacearea contact between the blade and the blade carrying body, impactforces are transferred through the blade, through the blade carryingbody and into the arrow shaft. The arrowhead structure according to thisinvention acts more as an integral unit as opposed to a conventionalblade-opening arrowhead wherein the impact forces are typicallytransferred through the pivot shaft or a similar component.

According to one preferred embodiment of this invention, the blade isheld in the normally closed position by contacting an engaging elementwith a portion of the blade. A bias force, such as from a springelement, is used to urge the engaging element against the blade.

In one preferred embodiment according to this invention, the engagingelement is a generally flattened tab which has a raised portion, whichis also referred to as an upset. In such preferred embodiment, eachblade has a recess and in the closed position, the raised portion orupset is mateably engaged within the recess. In such preferredembodiment, the spring element can be the generally flattened tabitself, acting as a leaf spring.

In another preferred embodiment according to this invention, thelocations of the raised portion and the recess can be interchanged sothat the recess is formed within the generally flattened tab and theraised portion is formed on the blade. It is also apparent that theraised portion and the recess can have any suitably shaped cross sectionor overall shape.

In one preferred embodiment according to this invention, the engagingelement is a plunger shaft that is slidably mounted within the bladecarrying body. In such preferred embodiment, the spring element is acoil spring mounted in such a manner that it normally urges the plungershaft toward a corresponding blade. The corresponding blade has a notchwhich is shaped to correspond to or accommodate the shape of the plungershaft. When the blade is in the normally closed position, the plungershaft is mated within the notch to prevent opening movement of theblade.

In the preferred embodiments of this invention as discussed above, thespring element is preferably designed so that a sufficient bias force isapplied to the blade in order to prevent the blade from pivoting out ofthe normally closed position, even when relatively small forces areapplied to the blade in an opening direction, such as when handling thearrowhead or during flight of the arrowhead. The spring element is alsodesigned so that the bias force is easily overcome when a moresignificant force is applied in the opening direction, such as when thearrowhead impacts a target.

Other preferred embodiments of the engaging element and the springelement will be discussed in the following description of thisinvention. The blade-opening arrowhead according to this inventionrequires no consumable element, such as an O-ring, a band, a wrap orother similar element, in order to maintain the blades in a normallyclosed position. Eliminating such consumable element associated withconventional blade-opening arrowheads improves the safety aspects of thearrowhead, significantly reduces the cost for using the arrowhead byeliminating the need for a user to purchase consumable goods, and alsoeliminates awkward handling of the arrowhead when attempting to installsuch conventional consumable element, particularly during atime-critical hunt.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and objects of this inventionwill be better understood from the following detailed description takenin conjunction with the drawings wherein:

FIG. 1 is a partial cross-sectional front view of a blade-openingarrowhead, exposing a pivotally mounted blade at least partially housedwithin a closed slot of a blade carrying body, with the blade in aclosed position, according to one preferred embodiment of thisinvention;

FIG. 2 is similar to FIG. 1, but with the blade in an open position;

FIG. 3 is a partial cross-sectional front view of the blade-openingarrowhead shown in FIG. 1, with the blade removed for clearly showingbias means used to maintain the blade in a normally closed position,according to one preferred embodiment of this invention;

FIG. 4 is a sectional view taken along line 4--4, as shown in FIG. 1;

FIG. 4A is a sectional view similar to the sectional view of FIG. 4, butwith a blade carrying body having two slots for housing twocorresponding blades;

FIG. 5 is a partial cross-sectional front view of a blade-openingarrowhead, exposing two pivotally mounted blades each in a closedposition, according to another preferred embodiment of this invention;

FIG. 6 is a partial cross-sectional front view similar to that shown inFIG. 5, but with the blades in a fully open position;

FIG. 7 is a partial cross-sectional front view of the blade-openingarrowhead shown in FIG. 5, with the blades removed for clearly showingbias means used to maintain the blade in a normally closed position,according to another preferred embodiment of this invention;

FIG. 8 is a sectional view taken along line 8--8, as shown in FIG. 5;

FIG. 9 is a partial cross-sectional front view of a blade-openingarrowhead, wherein bias means are mounted to the blade, according toanother preferred embodiment of this invention;

FIG. 10 is a partial cross-sectional front view of a blade-openingarrowhead, wherein bias means for maintaining the blade in a normallyclosed position comprise a spring-loaded plunger shaft, and the blade isin a fully closed position, according to another preferred embodiment ofthis invention;

FIG. 11 shows the same blade-opening arrowhead as shown in FIG. 10, butwith the blade in a fully open position;

FIG. 12 shows a partial cross-sectional front view of a blade-openingarrowhead, wherein bias means for urging the blade into a normallyclosed position comprise a spring-loaded bearing element, according toanother preferred embodiment of this invention;

FIG. 13 is a front view of a spring element, according to one preferredembodiment of this invention;

FIG. 14 is a sectional view taken along line 14--14, of the springelement as shown in FIG. 13;

FIG. 15 is a front view of a spring element, according to anotherpreferred embodiment of this invention;

FIG. 16 is a sectional view taken along line 16--16, of the springelement as shown in FIG. 15;

FIG. 17 is a sectional view taken along line 17--17, of the springelement as shown in FIG. 15;

FIG. 18 is a front view of a blade-opening arrowhead in a closedposition, wherein the blades are each mounted externally with respect tothe blade carrying body, according to one preferred embodiment of thisinvention;

FIG. 19 shows the same blade-opening arrowhead as shown in FIG. 18, butwith both blades in a fully open position; and

FIG. 20 is a side view of the blade-opening arrowhead shown in FIG. 19,looking in a direction from left to right.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1-4 show a blade-opening arrowhead, according to one preferredembodiment of this invention. As shown in FIGS. 1 and 2, pivot means areused to pivotally mount at least one blade 30, preferably 2-4 blades 30,with respect to blade carrying body 20. As clearly shown in FIGS. 1 and12, pivot shaft 40 is mounted with respect to blade carrying body 20.Each blade 30 preferably has a through hole or a blind bore within whichpivot shaft 40 is mateably mounted. By forming a relatively tightclearance between blade 30 and pivot shaft 40, blade 30 can easilyrotate about pivot shaft 40, without blade wobble. It is apparent thatthe contacting surfaces between pivot shaft 40 and blade 30 can bemachined or polished to provide a relatively tight tolerance withrelatively minimal friction. Once blade 30 is unlocked or released fromthe normally closed position shown in FIG. 1 and pivots towards thefully open position shown in FIG. 2, it is important for blade 30 toeasily pivot or free-wheel. Such easy pivoting or free-wheeling motionassures easy opening of blades 30 when the arrowhead impacts a target orwhen a sufficient opening force 28 is applied to blade 30.

Opening force 28 causes blade 30 to pivot in a clockwise direction, asshown in FIGS. 1 and 2, about pivot shaft 40. As the arrowhead impacts atarget, the target surface preferably impinges upon tip portion 31 ofblade 30 and thereby provides the necessary opening force 28 for movingeach blade 30 from the closed position to the open position. Openingforce 28 can be applied to blade 30 in any direction that does notintersect with center axis 41 of pivot shaft 40. Extending tip portion31 in the direction as shown in FIG. 1 increases the length of a momentarm between center axis 41 and opening force 28, which results in alesser force required to overcome the bias force applied to blade 30, asdiscussed below in more detail.

FIGS. 1-4 show, for reasons of clarity, the blade-opening arrowheadhaving only one pivotally mounted blade 30. The blade-opening arrowheadaccording to this invention will preferably have 2-4 blades 30 eachpivotally mounted with respect to blade carrying body 20. FIG. 4A showsa cross section of blade carrying body 20 having two closed slots 25 and27 within each of which is housed one pivotally mounted blade 30. FIG.4A also shows how two stationary blades 70 can be mounted with respectto blade carrying body 20, between both pivotally mounted blades 30. Itis apparent that one or more stationary blades 70 can be used with atleast one pivotally mounted blade 30.

The desired weight and overall size of the blade-opening arrowheadaccording to this invention will dictate the number of pivotally mountedblades 30 and stationary blades 70, if any. When a plurality of blades30 are used, such blades 30 should preferably be positioned so that theyevenly balance the arrowhead. For aerodynamic reasons, it is importantto have an arrowhead that is balanced along a centerline axis of bladecarrying body 20.

Pivot shaft 40 preferably has a generally circular cross section.However, it is apparent that pivot shaft 40 can have any other suitablecross section which can be used to pivotally mount blade 30 with respectto blade carrying body 20. Because of the increased bearing surface areabetween blade 30 and pivot shaft 40, which tends to prevent bladewobble, a generally circular cross section is preferred. Although pivotshaft 40 is preferably mounted within blade carrying body 20 so that noportion of pivot shaft 40 extends beyond skin surface 35 of bladecarrying body 20, it is apparent that at least a portion of pivot shaft40 could extend beyond skin surface 35 of blade carrying body 20, forexample as shown in FIGS. 18-20. Pivot shaft 40 can be mounted withinblade carrying body 20 so that pivot shaft 40 is either fixed or movablewith respect to blade carrying body 20.

FIGS. 5-8 show a blade-opening arrowhead according to another preferredembodiment of this invention. In the embodiment shown in FIGS. 1-4,blade carrying body 20 forms at least one closed slot 25, preferably twoclosed slots 25 and 27 as shown in FIG. 4A, which each house one blade30. In the embodiment shown in FIGS. 5-8, two blades 30 are each mountedwithin open slot 29, which extends entirely through blade carrying body20. Because an island or web 23 of material that remains between closedslot 25 and closed slot 27, in blade carrying body 20 housing two blades30, as shown in FIG. 4A, the structural strength of blade carrying body20 can be greater than the structural strength of blade carrying body 20having open slot 29 extending entirely through blade carrying body 20,as shown in FIG. 6.

According to this invention, engagement means are used to maintain blade30 in a normally closed position, as illustrated in FIGS. 1 and 5, forexample. Bias means are used to provide a bias force that is strongenough to urge the engagement means against blade 30 and maintain blade30 in a normally closed position, yet weak enough so that the magnitudeand direction of the bias force are easily overcome when opening force28 is applied to blade 30. Thus, according to this invention, blade 30can easily pivot or free-wheel from the fully closed position shown inFIGS. 1 and 5 to the fully open position shown in FIGS. 2 and 6.

According to one preferred embodiment of this invention, the engagementmeans comprise flexible member 50 deflectably mounted with respect toblade 30. As used throughout this specification and in the claims, thephrase deflectably mounted is intended to relate to flexible member 50mounted so that flexible member 50 can deflect in a particulardirection. Flexible member 50 preferably acts as a cantilever having onefixed end and an opposite deflectable free end. As shown in FIGS. 4, 8and 14, flexible member 50 is preferably constructed with plate materialor foil material which can be shaped to form raised portion 52. Raisedportion 52 may also be known as and referred to as an upset. Theengagement means preferably comprise blade 30 having recess 36 withinwhich raised portion 52 mates when blade 30 is in the normally closedposition. It is apparent that recess 36 can be a blind bore or a throughhole having a shape that corresponds to raised portion 52. It isapparent that raised portion 52 can have any suitable shape thatcorresponds and mates with recess 36.

As clearly shown in FIGS. 3, 7 and 14, flexible member 50 is preferablyformed as a leaf spring. The bias force within the leaf spring urgesraised portion 52 within recess 36, in the normally closed position ofblade 30. It is apparent that flexible member 50 may be formed from anyother suitable material, such as a bent wire or any other

Flexible member 50 is preferably connected to baseplate 56, as shown inFIGS. 3, 7, 13 and 15. Baseplate 56 is shown as being constructed ofgenerally flat plate material. However, it is apparent that baseplate 56can be constructed of any other material or have any other suitableshape which corresponds to the mating shape of blade carrying body 20,where baseplate 56 is positioned. As shown in FIG. 13, flexible member50 acts as a cantilever having one end fixed with respect to baseplate56 and an opposite free end urged toward blade 30.

When flexible member 50 is in a mounted position with respect to bladecarrying body 20, as shown in FIG. 3, side edge 57 of baseplate 56,shown in FIGS. 13 and 15, abuts sidewall 22 of blade carrying body 20.As shown in FIG. 13, according to one preferred embodiment of thisinvention, side edge 57 has a convex arcuate shape which corresponds tothe concave arcuate shape of sidewall 22. Thus, when pivot shaft 40 ismounted within through hole 58 of baseplate 56, the forward portion ofside edge 57 abuts the forward portion of sidewall 22 to preventcounterclockwise movement, relative to the orientation shown in FIG. 1,of baseplate 56 with respect to blade carrying body 20, as blade 30moves toward and into the normally closed position. Likewise, therearward portion of side edge 57 abuts the rearward portion of sidewall22, in order to prevent clockwise rotation of baseplate 56 with respectto blade carrying body 20, as blade 30 moves toward the fully openposition, as shown in FIG. 2. As clearly shown in FIG. 3, pivot shaft 40mounted within through hole 58 also provides an interference that limitslongitudinal movement of baseplate 56 with

Although not necessary, it is preferred that baseplate 56 remains in arelatively fixed position with respect to blade carrying body 20. Asshown in the mounted positions of FIGS. 3 and 7, baseplate 56 willactually move with respect to blade carrying body 20, to the extent ofthe tolerances between such components. It is apparent that baseplate 56can be fixedly secured with respect to blade carrying body 20 by usingadhesives, welding techniques, or any other suitable securement meansknown to those skilled in the art. It is even possible to extend andbend base plate 56 so that an edge portion of baseplate 56 extendsbeyond closed slot 25 or open slot 29 and over skin surface 35 of bladecarrying body 20. Maintaining the relative position of baseplate 56results in maintaining the relative position of flexible member 50 sothat raised portion 52 can properly align with and mate within recess36.

It is apparent that the roles between flexible member 50 and recess 36can be reversed so that flexible member 50, for example, is integralwith, connected to or otherwise attached to blade 30, and recess 36 isformed within blade carrying body 20 or an equivalent element. FIG. 9illustrates one preferred embodiment of this invention wherein such rolereversal is accomplished by flexible member 50 formed as an integralpart of blade 30 and recess 36 formed within blade carrying body 20.

FIG. 10 shows another preferred embodiment according to this invention,wherein the engagement means comprise plunger shaft 60 slidably mountedwithin a bore within blade carrying body 20. In such embodiment, thebias means preferably comprise spring 62 mounted with respect to bladecarrying body 20 so that in the closed position of blade 30, spring 62urges plunger shaft 60 into a mated position within notch 34 of blade30, as shown in FIG. 10. Plunger shaft 60 preferably has arcuate tip 61which mates within notch 34, so that as opening force 28 is applied toblade 30, movement of blade 30 overcomes the bias force and forcesplunger shaft 60 out of notch 34, thus allowing blade 30 to rotateclockwise, as shown in FIG. 10, toward the fully open position.

As shown in FIG. 11, when blade 30 is in the fully open position,plunger shaft 60 is fully extended toward blade 30 and seats within acorresponding notch 33. As shown by hidden lines in FIGS. 10 and 11,spring 62 is preferably a coil spring which is preferably mounted withinhousing 63.

In another preferred embodiment according to this invention, theengagement means comprise bearing member 65 slidably mounted withinblade carrying body 20, as shown in FIG. 12. Bias means, such as spring68, are used to urge bearing surface 67 within notch 34 of blade 30.Blade 30 is not shown in FIG. 12 but is preferably similar to blade 30shown in FIG. 1, for example.

Stop means are used to prevent pivotal movement of blade 30 fromproceeding further than the fully open position, as shown in FIGS. 2 and6. In one preferred embodiment according to this invention, the stopmeans comprise blade 30 having blunt edge 38, which is generallyopposite sharp edge 37, as shown in FIG. 2. FIG. 2 shows blunt edge 38abutting blade carrying body 20 at sidewall 22. Blade 30 preferablymakes surface contact with blade carrying body 20, so that impact forcesare transferred between blade 30 directly through blade carrying body 20and into an arrow shaft to which the blade-opening arrowhead of thisinvention is attached. It is desirable to minimize the forcestransferred through pivot shaft 40 in order to prevent unnecessary wearbetween blade 30 and pivot shaft 40.

In one preferred embodiment according to this invention, sharp edge 37abuts blade carrying body 20, as shown in FIGS. 1 and 5, when blade 30is in the closed position. However, it is apparent that flexible member50 and notch 34 can be designed so that sharp edge 37 does not contactblade carrying body 20 when blade 30 is in the normally closed position.

According to one preferred embodiment of this invention, blade carryingbody 20 has two closed slots 25 and 27, as shown in FIG. 4A. Closed slot25 and closed slot 27 are preferably offset with respect to each other,so that an island or web 23 of material, for example the same materialwhich forms blade carrying body 20, is positioned between closed slot 25and closed slot 27. Such arrangement of blade carrying body 20 resultsin a structural member that provides significantly increased strengthover blade carrying body 20 having open slot 29 passing completelythrough the member.

As shown in FIGS. 15-17, rib 54 is an integral part of but can also beconnected to or otherwise attached to baseplate 56 of flexible member50. Rib 54 provides a bearing surface over which blade 30 slides whenmoving between the open and closed positions. Rib 54 can be used toeliminate blade wobble by tightening any gap established betweenbaseplate 56 and blade 30.

FIGS. 18-20 show another preferred embodiment according to thisinvention wherein two blades 30 are each pivotally mounted with respectto blade carrying body 20, so that blade 30 is positioned entirelyexternal with respect to blade carrying body 20. In such preferredembodiment, pivot shaft 40 comprises a screw which is threadedly engagedwithin an internally threaded bore within blade carrying body 20.However, it is apparent that other mechanical elements can be used toaccomplish the same result of providing a shaft about which anexternally mounted blade 30 can pivot. As shown in FIG. 19, blade 30comprises recess 36 and flexible member 50 is either integral with ormounted to blade carrying body 20. It is apparent that the roles betweenrecess 36 and flexible member 50 can be reversed so that blade 30comprises flexible member 50 and so that blade carrying body 20 hasrecess 36. Blade 30 is preferably positioned adjacent mounting area 24which is preferably formed by machining or otherwise forming a flattenedsurface upon blade carrying body 20. Mounting area 24 is preferablygenerally parallel to a longitudinal axis of the arrowhead, so thatblades 30 remain generally parallel to such longitudinal axis and thusprevent undesirable steering of the arrowhead.

The bias means according to this invention are intended to comprise leafsprings, coil springs and/or any other suitable member that has a returnforce or a bias force. For example, the bias means may even comprise amaterial that returns to its initial shape after being bent, compressedor otherwise deformed. As another example of bias means, two blades 30can be pivotally mounted so that both blades 30 come relatively close toeach other at some point throughout pivotal movement. One of such blades30 can have raised portion 52 and the other blade 30 can have notch 34,resulting in engagement means to hold both blades 30 in a closedposition with respect to blade carrying body 20. In such preferredembodiment, the bias means can comprise a cantilever portion of oneblade 30 acting as a spring element when forced against the other blade30.

The blade-opening arrowhead according to this invention has severaloperational and performance advantages over conventional blade-openingarrowheads. For example, the engagement means according to thisinvention result in a snap locking blade retention system wherein theuser senses a positive snap action resulting from the bias means urgingthe engagement means against blade 30, such as when moving blade 30 intothe fully closed position. The bias means and engagement means accordingto this invention can be properly designed so that blade 30 releasesfrom the fully closed position, in an opening direction, immediately andresponsively when a sufficient opening force 28 is applied to blade 30.Because the bias means and engagement means of this invention maintainblade 30 in the closed position, once the bias force is overcome andblade 30 moves in the opening direction, blade 30 need not overcomeclosing forces, such as those applied by conventional O-rings, wraps orother annular bands. Once blade 30 according to this invention movesfrom the closed position, blade 30 free-wheels into the fully openposition, thereby exposing sharp edges 37. Because of the increasedbearing surface contact between blade 30 and blade carrying body 20according to this invention, forces are transferred through each blade30, blade carrying body 20 and the arrow shaft, as if such threeelements were an integral unit.

It is apparent that the components of the blade-opening arrowheadaccording to this invention can be constructed of relativelyhigh-strength materials, such as lightweight metals, graphite, graphitecomposites and other suitable materials known to those skilled in theart. Although certain components shown in the drawings may be identifiedas metal, plastic or composite, it is apparent that various materialscan be interchanged without departing from the desired results of ablade-opening arrowhead according to this invention. It is also apparentthat the different bias means, engagement means and pivot means can beinterchanged throughout the above-discussed and other preferredembodiments according to this invention, without departing from thedesired results.

While in the foregoing specification this invention has been describedin relation to certain preferred embodiments thereof, and many detailshave been set forth for purpose of illustration, it will be apparent tothose skilled in the art that the invention is susceptible to additionalembodiments and that certain of the details described herein can bevaried considerably without departing from the basic principles of theinvention.

We claim:
 1. In an arrowhead having a blade carrying body, theimprovement comprising:a blade having a through hole; engagement meansfor maintaining said blade in a closed position; bias means for urgingsaid engagement means against said blade and for allowing said blade topivot from said closed position upon an opening force applied to saidblade, said bias means comprising a baseplate; a pivot shaft mountedwith respect to the blade carrying body, said pivot shaft mounted withinsaid through hole; and said pivot shaft passing through said baseplateand a side edge of said baseplate engaging a sidewall of the bladecarrying body to maintain said baseplate in a mounted position withrespect to the blade carrying body.
 2. In an arrowhead according toclaim 1, wherein said pivot shaft has a generally circular crosssection.
 3. In an arrowhead according to claim 1 wherein said pivotshaft is completely positioned within the blade carrying body.
 4. In anarrowhead according to claim 1 wherein said engagement means comprise: aflexible member deflectably mounted with respect to said blade, saidflexible member having a raised portion, said blade having a hole, andwith said blade in said closed position said raised portion mateablewithin said hole.
 5. In an arrowhead according to claim 4 wherein saidbias means further comprise: said flexible member formed as a leafspring, and said leaf spring urging said raised portion within saidhole.
 6. In an arrowhead according to claim 1 further comprising stopmeans for stopping pivotal movement of said blade at an open position ofsaid blade.
 7. In an arrowhead according to claim 6 wherein said stopmeans comprise: said blade having a blunt edge, and in said openposition said blunt edge abutting the blade carrying body.
 8. In anarrowhead according to claim 7 wherein said blunt edge has an arcuateshape, the blade carrying body forms an arcuate edge, and in said openposition said blunt edge abuts said arcuate edge.
 9. In an arrowheadaccording to claim 1 wherein said blade has a sharp edge, and a tipportion of said blade is angled away from said sharp edge.
 10. In anarrowhead according to claim 1 wherein the blade carrying body has afirst closed slot and a second closed slot, said blade is at leastpartially mounted within said first closed slot, a second blade is atleast partially mounted within said second closed slot, and a structuralweb of the blade carrying body isolates said first closed slot withrespect to said second closed slot.
 11. In an arrowhead according toclaim 10 wherein said structural web is positioned between said firstclosed slot and said second closed slot.
 12. In an arrowhead accordingto claim 1 further comprising at least one stationary blade fixed withrespect to the blade carrying body.
 13. In an arrowhead having a bladecarrying body, the improvement comprising:a blade having a through hole;engagement means for maintaining said blade in a closed position; biasmeans for urging said engagement means against said blade and forallowing said blade to pivot from said closed position upon an openingforce applied to said blade, said bias means comprising a baseplate; apivot shaft mounted with respect to the blade carrying body, said pivotshaft mounted within said through hole; and the blade carrying bodyhaving a slot, at least a portion of said slot bound by a sidewall ofthe blade carrying body, in a mounted position of said baseplate atleast a portion of said baseplate positioned between said sidewall andsaid pivot shaft, and a side edge of said baseplate positioned adjacentsaid sidewall.
 14. In an arrowhead according to claim 13 wherein saidblade has an arcuate shaped blunt edge, the blade carrying body forms anarcuate edge, and in an open position of said blade said blunt edgeabuts said arcuate edge.